This is David Leatherhoff from the mod Afraid of Monsters, remade for Garry's Mod.
He is hexed and in Addon format so just stick the David Leatherhoff file into Garrysmod/addons/.

Model Hack by CrzyMLC
Skin by HWECQI/Vezon (moi)
Hexed by Jason278
Based on the mod by Team Psykskallar

I'd suggest getting this knife model too since he uses a knife almost exactly like it in the game
http://www.garrysmod.org/downloads/?a=view&id=85972

and no I will not make him into a player model before ANYONE asks.